1. Field of the Invention
The present invention relates to a light absorbing layer composition and a method for fabricating a semiconductor device using the composition. More particularly, the present invention relates to a composition for an anti-reflective light absorbing layer capable of preventing light reflection from a substrate during exposure in a photolithography process during the manufacture of an integrated circuit device and a method for forming patterns in a semiconductor device using the composition.
2. Description of the Related Art
With trends towards high-density semiconductor devices, a micro-process for forming ultrafine patterns, recently on submicron levels, in a photolithography process has been developed. In a lithography process, a photoresist layer is coated on a substrate and subjected to exposure and development processes to form a mask pattern. In general, the substrate has high-reflectivity material layers thereon. Accordingly, light passed through the photoresist layer is reflected by the substrate during exposure, especially when the substrate has a step, so that reflective notching, standing wave, critical dimension deviations of photoresist patterns may result. For this reason, a technique to use an anti-reflective coating capable of absorbing the wavelength of an exposure light source to prevent reflection from underlying layers has been suggested.
Anti-reflective coatings used in the manufacture of semiconductor devices are classified into two groups according to their materials, an inorganic anti-reflective coating and an organic anti-reflective coating. Unlike the inorganic reflective coating formed by chemical deposition, the organic reflective coating may be simply formed by spin coating, and thus its applications are increasing.
However, the organic reflective coating is similar to photoresist materials in its basic chemical structure and has a low etching selectivity with respect to a photoresist layer during dry etching. As a result, during etching to remove the organic anti-reflective coating, consumption of the photoresist layer is increased. Therefore, there is a need to increase the thickness of the photoresist layer when the organic reflective coating is introduced.
In general, smaller thickness of the photoresist layer for lithography results in higher resonance. Also, the lower the limit of resolution, the smaller the thickness of the photoresist layer for the purpose of preventing photoresist pattern collapsing. In view of this, the thickness of the photoresist layer for photolithography is limited by the incorporation of the organic anti-reflective layer.